Global Dynamics goes into lockdown to protect itself from the now airborne metal-eating bacteria. Stuck inside GD, Sheriff Carter and Stark must work together to save both the town and Kevin, Alison's son.

After tracking down the woman in the company photo, Peter travels to Primatech in Texas to destroy the virus, but not everything is what it seems. Hiro continues the pursuit of his father's killer. Niki is reunited with Micah, and Claire deals with the aftermath of her father's death. Finally, Maya has to choose to remain with Alejandro, or go with Sylar.

As Eva Thorne prepares to seal off the subterranean military complex, Zoe's life is endangered as her body begins to rapidly age.

Adam reveals that Riley has a behavior modification chip located just over his heart and wired into his central nervous system. Buffy realizes what Spike is doing and tries to pull the gang back together in time for a final showdown with Adam inside the Initiative itself.

Danny Farrell's newfound ability to spread promicin leads to several hundred deaths, including his mother. With Seattle in chaos, NTAC is forced to accept Promise City's offer of help. Shawn is faced with a difficult decision when Danny asks him to end his life to stop the spread of promicin.

Homer fears he may be a little slow, so he goes to the Adult Education Annex. While there, he decides to teach a class of his own on the secrets of a successful marriage, since that is the only thing he is good at.